1. Field of the Invention
This invention relates to a method of handling cylindrical objects and, more particularly, to a method of feeding, inspecting, and sorting drills. This invention also relates to apparatus for performing such methods.
2. Description of the Prior Art
Large machine shops and air frame manufacturers are required to re-grind thousands of drills each day as a result of wear on drills resulting from normal use. The importance of re-grinding drills for quality point geometries is well known. An efficient program for maintaining well ground drills can improve the through-put capacity of the machine shop, reduce labor requirements, increase the lives of the drills, reduce hole rework, improve the quality of the drilled holes, and improve the fatigue life of the products in which the holes are made. An efficient program can also reduce the grind shop load and thus extend the lives of the grinding machines. Without an efficient drill evaluation system, there is typically a needless re-grinding of drills which are not worn, an artificial backlog of drills, and added wear on the drill grinders which results in inconsistent and inaccurate drills significantly affecting rework costs and the quantity of the products.
It must be realized that it is not sufficient to merely send drills to re-grind on a periodic time or use basis since drills are normally sent from the production line, not only because of wear from normal usage over a period of time, but frequently because of chip and sealant clogging as well as for other non-wear related failures.
Many techniques exist for the implementation of the feeding, inspection, and sorting of cylindrical objects, such as drills for a re-grind program, and many techniques have been attempted in the past. Prior patent disclosures illustrate such techniques and document the development of this technology to the highly developed state that it enjoys today. For example, U.S. Pat. Nos. 2,502,503 to Berkley; 3,025,747 to Casselman, et al; and 3,405,578 to Persson all involve merely one-dimensional vision detecting of the sharpness of edges on razors, knives, and the like. More specifically, the patent to Berkley shows an apparatus employing optical means for testing the sharpness of objects such as razor blades. An oscilloscope provides the readout. Electronic circuitry may automatically reject blades found to be dull beyond certain tolerance limits. The patents to Casselman, et al and to Persson also teach optical means for determining the sharpness of linear cutting edges.
Patents directed to the movement of parts include U.S. Pat. Nos. 3,200,964 to Eldred; 3,730,364 to Nakamura et al; and 3,841,499 to Bullard. More specifically, the patent to Nakamura et al teaches a device having a manipulator for selecting samples for analysis and sequentially placing the samples into appropriate receptacles. The other two patents do not involve the vision inspection and sorting of parts
Vision applications can also be found in the patent literature. U.S. Pat. No. 4,420,253 to Pryor shows an optical means for detecting wear or breakage of a tool which could be a drill. This process uses fiber optics which are internal to the tool except in the instance of a worn or broken tool. The wear detecting means is connected through a microprocessor to a robot tool changing means. U.S. Pat. No. 4,344,146 to Davis et al does not employ plural cameras to determine drill type and wear.
U.S. Pat. Nos. 4,359,815 to Toyoda and 4,402,053 to Kelley et al disclose the use of robots as parts of systems. The patent to Toyoda shows the use of a robot manipulator arm to carry out tool exchanging and machining operations on a workpiece and workpiece manipulation in sequence with the two operations not interfering with each other. Used tools are placed in moving storage magazines. The patent to Kelley et al uses optical means combined with a robot manipulator arm to measure and determine the orientation of a workpiece.
Systems involving a part presentation, inspection, and sorting application are disclosed in U.S. Pat. No. 4,457,622 to Kato et al; Canadian Pat. No. 961803 to Bomemeier; and in U.S. Pat. No. 4,527,326 to Kohno et al. The patent to Kato et al shows a screw inspection device comprising a feed supply, transfer means, a plurality of optical sensors including laser light sources and signal processing means whereby a threaded fastener such as a screw or bolt can be measured against predetermined tolerances for length, diameter, and the presence and angle of threads. Items not within the preset tolerances can be rejected from the stream of parts. This patent does contact inspection on screws. The Canadian Patent shows an optical inspection and classifying means for determining the physical characteristics of a moving item such as a threaded fastener Items outside the tolerance limits are transferred out of the parts stream. The patent to Kohno et al shows an optical sorting system comprising a sorting device, an image detecting device such as a television camera, and an image processor connected to a robot manipulator arm. The presence of parts within specifications causes the manipulator arm to transfer the parts to another point in the system. This patent has a parts hopper with random parts, a robot, a vision system, and a sorting application. This is a general system and applies to assembly parts.
As is illustrated by the great number of prior patents, efforts are continuously being made in an attempt to solve the problem of feeding, inspecting, and sorting cylindrical objects such as drills. None of these patents, however, discloses or suggests the present inventive combination of elements and method steps for reliably, conveniently, accurately, rapidly, and economically feeding, inspecting, and sorting drills as disclosed herein. The present invention achieves its purposes, objectives, and advantages over the prior art through new, useful, and unobvious elements, with a minimum number of functioning parts, at a reduction of cost, and through the utilization of only readily available materials and conventional components.
These objects and advantages should be construed as merely illustrative of some of the more prominent features and applications of the present invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or by modifying the invention within the scope of the disclosure. Accordingly, other objects and advantages as well as a fuller understanding of the invention may be had by referring to the summary of the invention and detailed description describing the preferred embodiment of the invention in addition to the scope of the invention as defined by the claims taken in conjunction with the accompanying drawings